This invention relates to improvements in blind fastener devices and more particularly to such devices primarily used to secure two or more panel members together.
Various types of blind fasteners have been developed including the well known "pop-rivet" fasteners such as those commonly used for aircraft in holding together metal structures. Heretofore, such "pop-rivet" fasteners were unsatisfactory for securing together panel members of relatively soft material such as plaster board, primarily because the inner, enlarged end of the pop-rivet could not be made large enough to provide a secure anchor and resist being pulled through the rivet hole. Other fasteners developed for relatively soft materials such as the well known "molly-bolt" are often effective but have several disadvantages. For example, they usually require a fairly large pre-drilled hole through the panel materials and thereafter a screw member must be turned by a considerable amount in the usual time-consuming manner to deform and seat the retaining legs. Also, such "molly-bolt" devices are relatively complicated structurally and hence expensive, a not insignificant factor where large numbers of such fasteners are required.